1. Field of the Invention
The present invention relates to a recording/reproducing apparatus for recording and reproducing signals of e.g. video, audio, or other information data on a tape-like recording medium such as a magnetic recording tape and, more particularly to, a recording/reproducing apparatus capable of editing the recorded data. The editing function alters the recorded data by replacing or erasing given recording area and adds continuous data to succeeding recording areas after the given recording area.
2. Description of the Prior Art
A variety of magnetic recording/reproducing apparatuses, such as video taperecorders (referred, to as VTRs, hereinafter have been developed and practically used which utilize magnetic recording tapes. Manufacturer efforts have results in size reductions, improved for high density recording, and digital recording. In such devices it is essential for increasing the recording density and maintaining compatibility to allow a magnetic head to perform accurate tracking actions. For this purpose, a tracking control method termed ATF has been introduced for use with a VTR in which a pilot signal is multiplexed onto a data signal during recording and utilized for correct tracking action during retrieval of the data signal. A conventional magnetic recording/reproducing apparatus using such a tracking control method will now be described.
In a recording mode, a row of oblique recording tracks are formed on a magnetic recording tape by a magnetic head mounted on a rotary cylinder. A recording signal fed to the magnetic head contains a data signal frequency multiplexed with pilot signals for tracking control. More particularly, two different pilot signals having frequencies of f1 and f2 respectively are recorded alternately onto every two recording tracks. Commonly, the frequency of each pilot signal is selected from four typical low frequencies which will minimize interference with the data signal.
The action of tracking the such recording tracks in a reproducing mode will be explained. As the magnetic head traces a target track, it reads a segment of the data signal and simultaneously, detects two pilot signal components f1 and f2 of the adjacent recording tracks. The relative position of the magnetic head to the target recording track can hence be examined through comparing the two pilot components f1,f2. In more detail, the two pilot components f1,f2 are extracted through a bandpass filter and converted by an AM detection circuit to their respective DC components depending on their amplitudes. The two DC components are then compared by a subtraction circuit. A resultant output of the subtraction circuit is a tracking error signal denoting a positional difference between the magnetic head and the target track to be traced. Upon receiving the tracking error signal, a capstan motor control circuit for controlling the feeding of a tape actuates a capstan motor to control the tape running so that the magnetic head traces along the center of the target track.
For replacement of the recorded data signal on a magnetic recording tape with another data signal (which will be termed as insert editing), the reproducing mode is shifted to the recording mode at a point of rewriting and the new data signal is recorded while the existing data signal is being erased. More specifically, the new data signal is recorded onto the recording tape, track, by track at the timing determined by a signal from a rotating position detecting sensor mounted to the rotary cylinder.
According to the conventional magnetic recording/reproducing apparatus, the start point of recording on each track for the insert editing action is determined by the signal of the rotating position detecting sensor of the rotary cylinder and thus, the existing data signal in the track will hardly be erased in its entirety due to mechanical non-uniformity and setting error. The remaining data which has not been erased may result in malfunction of the entire apparatus. Also, excessive erasing in the same track will likely be caused during partial rewriting. Particularly, editing with another recording/reproducing apparatus may create more error data thus degrading the performance of the apparatus. Also, the tracking is conducted using pilot signals multiplexed with the data signal according to the conventional apparatus and thus, no tracking control data will be given during the insert editing action. This may result in failure in the time matching between a current track and a preceding track at the end of editing, sequence error of the tracking data carried on the data signal, and development of imperfect track widths.